Key cutting machines are of two general types, either the duplicating type or the code cutting type. Duplicating type machines generally utilize a follower riding along the bittings (notches) of an existing key to guide the path of a cutter wheel which cuts a key blank. The present invention relates to code cutting type machines which are used by locksmiths to cut key blanks in the absence of an existing key which can be duplicated. Code books are published listing the longitudinal spacing of the notches along the blade of the key blank and the depth increments of the notches for keys which are utilized to open substantially all types of locks. By following the specifications in the code books, a locksmith can manually cut the proper notches in a key blank to duplicate a lost or misplaced key, but such manual cutting is time-comsuming and expensive.
Machines which are particularly adapted to code cutting have been provided, but, the known machines are all of the type wherein code cutting is accomplished with preformed and replaceable cams, plates, or discs which are used to control the relative movement and positions of the key blank and the cutter. With these prior art machines, a set of removable cams, plates, or discs is provided for each different type key. When a key for a particular lock is to be cut, the set of cams, plates or discs corresponding thereto is placed on the machine and is used to control the relative travel of a key blank which is brought into cutting engagement with a cutter such that the notches will be cut at the proper intervals and to the proper depths.
Because of the large number of lock manufacturers, and the many different types of locks manufactured by each manufacturer, a full complement of such prior art cams, plates or discs represents an expensive investment and less than a full complement tends to limit the use of the prior art machines. Moreover, many of these coded cams, plates and discs are not readily available for a large number of locks now in common use.